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排序方式: 共有466条查询结果,搜索用时 15 毫秒
71.
Evidence of long distance airborne transport of porcine reproductive and respiratory syndrome virus and Mycoplasma hyopneumoniae
总被引:1,自引:0,他引:1
The ability of porcine reproductive and respiratory syndrome virus (PRRSV) and Mycoplasma hyopneumoniae to be transported over long distances via the airborne route was evaluated. A source population of 300 grow-finish pigs was experimentally inoculated with PRRSV MN-184 and M. hyopneumoniae 232 and over a 50-day period, air samples were collected at designated distances from the source herd using a liquid cyclonic collector. Samples were tested for the presence of PRRSV RNA and M. hyopneumoniae DNA by PCR and if positive, further characterized. Of the 306 samples collected, 4 (1.3%) were positive for PRRSV RNA and 6 (1.9%) were positive for M. hyopneumoniae DNA. The PRRSV-positive samples were recovered 4.7 km to the northwest (NW) of the source population. Four of the M. hyopneumoniae-positive samples were obtained at the NW sampling point; 2 samples at approximately 2.3 km and the other 2 samples approximately 4.7 km from the source population. Of the remaining 2 samples, one sample was obtained at the southeast sampling point and the other at the southwest sampling point, with both locations being approximately 4.7 km from the source. The four PRRSV-positive samples contained infectious virus and were ≥ 98.8% homologous to the MN-184 isolate used to inoculate the source population. All 6 of the M. hyopneumoniae-positive samples were 99.9% homologous to M. hyopneumoniae 232. These results support the hypothesis that long distance airborne transport of these important swine pathogens can occur. 相似文献
72.
Gabriele Vaccari Cynthia H. Panagiotidis Cristina Acin Simone Peletto Francis Barillet Pierluigi Acutis Alex Bossers Jan Langeveld Lucien van Keulen Theodoros Sklaviadis Juan J. Badiola Olivier Andr��oletti Martin H. Groschup Umberto Agrimi James Foster Wilfred Goldmann 《Veterinary research》2009,40(5)
Scrapie is a fatal, neurodegenerative disease of sheep and goats. It is also the earliest known member in the family of diseases classified as transmissible spongiform encephalopathies (TSE) or prion diseases, which includes Creutzfeldt-Jakob disease in humans, bovine spongiform encephalopathy (BSE), and chronic wasting disease in cervids. The recent revelation of naturally occurring BSE in a goat has brought the issue of TSE in goats to the attention of the public. In contrast to scrapie, BSE presents a proven risk to humans. The risk of goat BSE, however, is difficult to evaluate, as our knowledge of TSE in goats is limited. Natural caprine scrapie has been discovered throughout Europe, with reported cases generally being greatest in countries with the highest goat populations. As with sheep scrapie, susceptibility and incubation period duration of goat scrapie are most likely controlled by the prion protein (PrP) gene (PRNP). Like the PRNP of sheep, the caprine PRNP shows significantly greater variability than that of cattle and humans. Although PRNP variability in goats differs from that observed in sheep, the two species share several identical alleles. Moreover, while the ARR allele associated with enhancing resistance in sheep is not present in the goat PRNP, there is evidence for the existence of other PrP variants related to resistance. This review presents the current knowledge of the epidemiology of caprine scrapie within the major European goat populations, and compiles the current data on genetic variability of PRNP. 相似文献
73.
Life cycle assessment (LCA) can be an objective, strategic and immediate criteria in determining, case-by-case, the most suitable crop for energy. In this study, a cradle-to-farm gate LCA study was performed in 4 perennial energy crops and then compared to the environmental impacts of a conventional wheat–maize rotation. The functional units energy and hectare were used for ranking the crops. The results showed clear and constant environmental benefits, on average 50% lower impacts, by substituting the conventional rotation with perennial crops. Among the latter, little differences were found on hectare basis, while the differences were strictly dependent on biomass yield, on energy basis. Giant reed, the most productive crop, showed at this regard the best performance, while cynara resulted in the lowest ecological benefits. A similar trend was also registered as concern the energy gain and efficiency that ranged from 75 (cynara) to 349 (giant reed) GJ ha−1, and from 7 to 30 (same order), respectively. On hectare basis, switchgrass achieved better results in six categories out of nine, and especially, it was from 27% to 32% less impacting than the other perennials on marine water ecotoxicity, which resulted in the clearly most affected category after normalisation on average European inhabitants. Weighting is not allowed for public comparison (ISO 14042), yet it can be helpful for some overall indications and conclusive comments. Comparing giant reed and switchgrass under different weighting sets, it emerged that resource depletion was the main discriminator for crop choice. Evenly weighting human health (HH), resource depletion (RD) and ecosystem quality (EQ) categories made the preference toward switchgrass or giant reed very uncertain. Taking three different weighting sets with RD, HH and EQ having 50% of relative importance (25% was set for the remaining two categories), switchgrass appeared the best choice in two cases (i.e. HH = 50% and EQ = 50%) out of three. Therefore, the preference toward a specific energy crop will strongly depend on weighting sets that may considerably change in space and time. 相似文献
74.
Simone TelesJosé Alberto Pereira Carlos H.B. SantosRenata V. Menezes Ricardo MalheiroAngélica M. Lucchese Franceli Silva 《Industrial Crops and Products》2012,37(1):247-252
Lippia alba (Mill.) N.E. Brown, the ginger grass, is a medicinal and aromatic plant widely used in Latin America. In this work the effect of the geographical origin and different drying methodologies on L. alba leaves production, essential oil content and composition were evaluated. Field experiments were conducted in three different municipalities (Amargosa, Cruz das Almas and Santo Antônio de Jesus) from Bahia region (Brazil) and two drying methodologies (traditional and artificial with controlled conditions) were assessed. Fresh and dried leaves essential oils were extracted by hydro-distillation and their volatiles were determined by gas chromatography.The geographical origin affected the mass production, essential oil content and both qualitative and quantitative fractions of their composition. Leaves from Cruz das Almas had higher yield in essential oil content. Overall, 26 oil constituents were identified. Carvone, germacrene D and limonene were the main oil constituents. The drying methodologies combined with the geographic origin influenced essential oil composition showing that L. alba constituents were influenced by post-harvest treatments. Some constituents were sensitive to both methods applied, while some enhanced their content like germacrene D. 相似文献
75.
The aim of this paper was to give a basic understanding of studies on methane emissions of New Zealand, as we know the agriculture of New Zealand is pastoral farming, most livestock animals are grazed in pasture, and quantities of methane were released from the digestive tract and animals excreta. In New Zealand some 50% greenhouse gases (GHG) sources are attributed to agriculture and one third is methane from livestock enteric formation. For many years, many researchers have been exploiting the techniques and methods to measure the emission of methane of New Zealand, further more studing the available options to alleviate the methane emissions. Their pioneering work and successful experiences including the determined methods and mitigation strategies are worth learning for scholars around the world. Some of their approaches were not only suitable for New Zealand grazed livestock, but for many other countries, even the animals are intensively bred in pen. The calorimeter/respiration chamber is the most exactly method in present, but it needs expensive equipments and skilled manipulators, so there are still some difficulty in applying this approach extensively in practice. Sulfur hexafluoride (SF6) trace technique is much adopted for grazed livestock evaluating the methane emission, though its veracity was doubted by some researchers, it is still a good option in present for studying the GHG emissions for grazing animals. By measuring the rumen volatile fatty acid (VFA) concentration to estimate the methane emission is a relatively simple approach, it is just only a rough evaluation, and it is unsuitable for exact study, but this method may be used in China for extensively raised ruminant. In present China, the ruminants are fed in an extensively managed state, the diversities of roughage and animals varieties caused difficult to exactly estimate the methane emission. So exploiting the available options is much important for constituting the exhaustive emission inventory. This review just maybe a good reference for researchers to carry out their studies in years and acquired great achievements in methane mitigation area. outline some practical techniques of New Zealand, those this field, after all New Zealand have been persisting many 相似文献
76.
IMAGING DIAGNOSIS—ULTRASONOGRAPHIC APPEARANCE OF SKELETAL MUSCLE METASTASES IN A DOG WITH HEMANGIOSARCOMA 下载免费PDF全文
Martina Fabbi Stefano Di Palma Sabrina Manfredi Giacomo Gnudi Francesca Miduri Eleonora Daga Gabriele Costantino Melis Ezio Bianchi Simone Voccia Antonella Volta 《Veterinary radiology & ultrasound》2017,58(6):E64-E67
A 13‐year‐old spayed female German shepherd dog was presented for acute onset of lethargy, anorexia, and disseminated erythematous skin lesions. Thoracic radiographs and abdominal ultrasonographic findings were consistent with metastatic hemangiosarcoma. Multiple, ill‐defined, irregularly shaped hypoechoic nodules were also detected within the thoracic and abdominal wall. Hemangiosarcoma metastases to the skeletal muscle were confirmed based on histopathological examination. Multivisceral involvement was also confirmed by necropsy. Metastatic neoplasia should be considered as a differential diagnosis for dogs with ill‐defined, irregular, hypoechoic, intramuscular nodules. 相似文献
77.
Nathan J Baker Simone Dahms Ruan Gerber John Maina Richard Greenfield 《African Zoology》2017,52(1):43-53
Studies on metal pollution (cadmium, cobalt, chromium, copper, manganese and nickel) in South African terrestrial environments are severely lacking. Due to being relatively unaffected by industrialisation, the Thohoyandou region may provide data on natural levels of metals for use as baseline data. The House Sparrow (Passer domesticus) was chosen as a bio-indicator of metal pollution due to its abundance, non-migratory lifestyle and close association with humans. The aims were to determine the viability of using feathers as a non-lethal bio-indicator tissue compared with muscle. Plume feathers, flight feathers and muscle tissue were analysed using ICP-OES techniques. Analyses of tissue metal concentrations identified the following trend: plume feather > flight feather > muscle tissue. Within the Thohoyandou region, Magondi, which was affected by anthropogenic activities at the time of sampling, had significantly higher concentrations (p ≤ 0.05) for each of the metals, indicating potential metal contamination from various sources. Alternatively, Makonde had the lowest metal concentrations and may be an important reference site for future comparative studies. The results showed that the House Sparrow can be used as a bio-indicator organism in South African terrestrial environments. The plume feathers indicate that they are a good non-lethal tissue for determining metal pollution levels on a temporal scale, indicating recent metal exposure. 相似文献
78.
Positive PCR alone should not be considered sufficient to establish Dirofilaria repens as the cause of subcutaneous nodular lesions in the absence of a clear cytologic picture 下载免费PDF全文
79.
Jose V. Moris Giorgio Vacchiano Simone Ravetto Enri Michele Lonati Renzo Motta Davide Ascoli 《New Forests》2017,48(5):663-683
European larch is a dominant species in the subalpine belt of the western Alps. Despite recent increases in wildfire activity in this region, fire ecology of European larch is poorly understood compared to other larch species around the world. This study aims to assess whether European larch forests are resilient to fires, and to find out the factors that drive such resilience. We assessed the recovery of larch forests along a gradient of fire severity (low, moderate, high) based on the abundance and dominance of post-fire larch regeneration. We established 200 plots distributed among burned larch forests in nine wildfires that occurred between 1973 and 2007 in the western Alps. We included variables regarding topography, climate, fire severity, fire legacies, ground cover, grazing intensity, and time since fire. To evaluate potential drivers of larch recruitment, we applied generalized linear mixed models (GLMM) and random forests (RF). Larch regeneration was much more abundant and dominant in the moderate- and high-severity fire classes than in the low-severity class. More than half of the plots in the moderate- and high-severity classes were classified as resilient, i.e., post-fire larch regeneration was enough to recover a larch stand. GLMM and RF produced complementary results: fire severity and legacies, such as snags, canopy cover and distance to seed source, were crucial factors explaining post-fire larch recruitment. This study shows that fire has a positive effect on larch regeneration, and we conclude that European larch forests are highly resilient to mixed-severity fires in the western Alps. 相似文献
80.
Maike?Krauss Hans-Martin?KrauseEmail author Simone?Spangler Ellen?Kandeler Sebastian?Behrens Andreas?Kappler Paul?M?der Andreas?Gattinger 《Biology and Fertility of Soils》2017,53(1):49-59
Since the development of effective N2O mitigation options is a key challenge for future agricultural practice, we studied the interactive effect of tillage systems on fertilizer-derived N2O emissions and the abundance of microbial communities involved in N2O production and reduction. Soil samples from 0–10 cm and 10–20 cm depth of reduced tillage and ploughed plots were incubated with dairy slurry (SL) and manure compost (MC) in comparison with calcium ammonium nitrate (CAN) and an unfertilized control (ZERO) for 42 days. N2O and CO2 fluxes, ammonium, nitrate, dissolved organic C, and functional gene abundances (16S rRNA gene, nirK, nirS, nosZ, bacterial and archaeal amoA) were regularly monitored. Averaged across all soil samples, N2O emissions decreased in the order CAN and SL (CAN?=?748.8?±?206.3, SL?=?489.4?±?107.2 μg kg?1) followed by MC (284.2?±?67.3 μg kg?1) and ZERO (29.1?±?5.9 μg kg?1). Highest cumulative N2O emissions were found in 10–20 cm of the reduced tilled soil in CAN and SL. N2O fluxes were assigned to ammonium as source in CAN and SL and correlated positively to bacterial amoA abundances. Additionally, nosZ abundances correlated negatively to N2O fluxes in the organic fertilizer treatments. Soils showed a gradient in soil organic C, 16S rRNA, nirK, and nosZ with greater amounts in the 0–10 than 10–20 cm layer. Abundances of bacterial and archaeal amoA were higher in reduced tilled soil compared to ploughed soils. The study highlights that tillage system induced biophysicochemical stratification impacts net N2O emissions within the soil profile according to N and C species added during fertilization. 相似文献